As building materials including house equipments and interior materials such as furniture, top plates for desks, various counters and doors, there have been extensively used decorative plates generally formed by shaping a synthetic resin-based material, for example, melamine resin decorative plates, etc.
Hitherto, as thermosetting resin decorative plates having an irregular shape on a surface thereof, there are known those decorative plates whose surface is formed into an irregular shape by using an embossed metal mold or an irregular resin sheet, and those decorative plates whose surface is formed into an irregular shape by using a shaping sheet. However, when using the embossed metal mold having an irregularity on a surface thereof, it is required to subject the metal mold to surface treatments such as blasting and etching, resulting in limitations to fineness of the irregular shape or pattern formed on the decorative plates. In addition, upon producing the decorative plates made of thermosetting resins, an expensive mold plate as well as a spare mold plate are needed, resulting in increased burden of time and costs for production of the decorative plates. Thus, owing to considerable increase in the production costs, the obtained products tend to become very expensive. Also, when using the irregular resin sheet, since the sheet is hardly peeled or separated from the thermosetting resin decorative plates after the resin is cured, it is required that an aluminum foil, a polypropylene film or the like is interposed between the sheet and the mold plate, thereby making it very difficult to form a fine irregular pattern with a good sharpness.
Meanwhile, with the recent tendency of consumers toward high-grade products, furniture or desks as well as interior materials have been required to show a high-grade feeling. The decorative plates used in these products have also been demanded to exhibit a good appearance with a high-grade feeling. For this reason, it becomes important to impart a good texture to these products, and there have been proposed various methods for imparting fine irregular patterns to the decorative plates.
For example, there has been proposed the shaping sheet including a substrate sheet provided on a surface thereof with an irregular shape made of an ionizing radiation-curable resin in which a crosslinking density of the resin is adjusted so as to prevent the irregular shape from being broken or cracked when peeling or separating the shaping sheet from a material to be shaped, thereby faithfully reproducing a desired pattern on the material, and allowing the shaping sheet to be usable repeatedly (refer to claims of JP 7-164519A). However, since the method for production of the shaping sheet includes a step of peeling or separating the shaping sheet from an intaglio printing roll, expression of the irregular shape having fine concave portions tends to be possible only in a limited range.
Thus, the above method has such a problem that when the concave portions to be formed are very fine, neat irregular patterns are not attainable. If concave portions to be formed are thick to a certain extent, it will be possible to form an irregular shape on a surface of the substrate. However, in this case, there tend to arise problems such as formation of convex portions having a larger height than that of the raised portions, which results in lacking of reality, for example, in the case of woodgrain patterns, and poor appearance and touch feeling.
In addition, there has been proposed the shaping sheet including a substrate sheet and an irregular pattern layer formed on a surface of the substrate sheet by using a resin composition composed of an inorganic filler and a binder resin, wherein the irregular pattern layer is formed by repelling only the resin composition for forming the fine irregular pattern layer which is applied onto a pattern of a liquid repelling resin formed on the substrate sheet (refer to claims of JP 5-92484A). However, since the irregular pattern layer is formed by repelling the resin composition for forming the irregular pattern layer, the pattern formed by the irregular shape tends to become unstable. Further, since the resultant sheet must be aged for a predetermined period of time to cure the irregular pattern layer, there tends to arise such a problem that the production of the shaping sheet requires a very long time, thereby failing to quickly meet various needs of consumers.